There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

This review focuses on inverter technologies for connecting photovoltaic (PV) modules to a single-phase grid. The inverters are categorized into four classifications: 1) the number of power processing stages in cascade; 2) the type of power decoupling between the PV module(s) and the single-phase grid; 3) whether they utilizes a transformer (either line or high frequency) or not; and 4) the type of grid-connected power stage. Various inverter topologies are presented, compared, and evaluated against demands, lifetime, component ratings, and cost. Finally, some of the topologies are pointed out as the best candidates for either single PV module or multiple PV module applications.

A review of single-phase grid-connected inverters for photovoltaic modules

A large scale Photovoltaic (PV) distributed energy resource (DER) connected to grid is studied in this paper. A single-stage power converter is considered in this study, which is capable of tracking maximum power point and controlling reactive power. The internal controller of the inverter has dynamic quadrature component to adjust the reactive power dispatch. The external voltage control tracks the maximum power point through dynamic reference value for the DC voltage. A comparison is conducted between variable and fixed DC reference voltages in terms of their active power yields for the proposed single stage converter system. The paper investigates the impact of different ambient disturbances such as varying weather conditions, solar radiation with severe disturbances. The active and reactive power flow and voltage of the system at three different distances of distribution line has been investigated and verified by Matlab/Simulink simulations.

Effects of large scale photovoltaic source on low voltage network under ambient disturbances and different distribution line distance

We report the synthesis and characterization of DSSCs based on N719 dye and ZnO nanorods. The nanorods were synthesized on fluorine doped tin oxide coated glass (FTO) substrate via chemical bath deposition method at 85 °C using zinc nitrate hexahydrate and hexamethylenetetramine. Prior to nanorods deposition, the substrates were coated with ZnO seed layer by spray pyrolysis technique. Our ZnO nanorods showed the hexagonal wurtzite structure and preferentially grew along the (002) direction. The lattice spacing between the crystal planes is estimated to be around 0.26 nm. The overall energy efficiencies of our DSSCs are ranged from 0.17% to 1.47%. These devices are found to be highly dependent on the dimensions of the ZnO nanorods. The best efficiency is obtained from solar cells composed of nanorods grown using 0.01 M precursor concentration, displaying 505 mV open circuit voltage, 6.415 mA/cm2 short-circuit current and 1.47% overall conversion efficiency.

Chemically grown ZnO nanorods for dye-sensitized solar cells

Thermal Stability and Light Transmission Capability of Nano TIO2 Enhanced Phase Change Material as Thermal Energy Storage

Spinel LiNi0.5Mn1.5O4 (LNMO) cathode are effectively obtained by one-pot hydrothermal synthesis. Scanning electron microscopy (SEM) reveals the hybrid morphological of LNMO, featuring cotton-like structures (400–800 nm) and rod-like structures (90–150 nm). The equivalent circuit well describes the Nyquist plot to separate the grain and grain boundary effects. According to the Maxwell-Wagner model, the complex permittivity confirms non-homogenous layers' existence; highly conducting grains and poorly conducting grain boundaries. Non-overlapping polar tunneling (NSPT) and correlated barrier hopping (CBH) are two responsible models for the conduction mechanism at low and high temperatures. Further, identical activation energy values are observed for hopping frequency, and peak frequency from normalized parameters Z’’/Z’’ max and M’’/M’’ max, suggesting Li+ ions are the dominant charge carriers. The LNMO/Li cell delivers higher discharge capacity than commercial LNMO/Li cell from prior study, credits from the bridging features between rod-like and cotton-like particles.

Structural, electrical and electrochemical characterization of hybrid morphological LiNi0.5Mn1.5O4 cathode material

The photovoltaic thermal (PVT) system was initially developed by attaching a simple sheet and tube thermal collector to the PV panel to improve cell performance while producing heat energy. The collector designs and heat transfer fluid are the main focus of PVT research, with the sheet and tube collector being the direct reference, and nanofluid being the promised working fluid. This study intends to review the development of the sheet and tube PVT (ST-PVT) system reported by researchers in the literature by searching and selecting quality literature from reputable academic databases guided by set criteria to maintain the consistency and validity of the literature selection. The findings indicate that the ST-PVT system with no glazing and a serpentine collector offers the most desirable thermal and electrical performance. It is also learned that CuO/water nanofluid enhances ST-PVT overall efficiency at a higher rate. However, it is observed that nanofluid required more pumping power, up to 67% for 0.4 wt% SiO2/water concentration compared to water. Also, many ST-PVT studies are only in the numerical modeling stage, while the negative impact of nanofluids is still rarely discussed in the literature. Thus, more research is required to prove the advantages of the ST-PVT system, especially in collector design and nanofluid application.

/pdf/global-advancement-of-nanofluid-based-sheet-and-tube-30etyjof.pdf

Nasrudin Abd Rahim

Papers

Effects of large scale photovoltaic source on low voltage network under ambient disturbances and different distribution line distance

Chemically grown ZnO nanorods for dye-sensitized solar cells

Thermal Stability and Light Transmission Capability of Nano TIO2 Enhanced Phase Change Material as Thermal Energy Storage

Structural, electrical and electrochemical characterization of hybrid morphological LiNi0.5Mn1.5O4 cathode material

Global Advancement of Nanofluid-Based Sheet and Tube Collectors for a Photovoltaic Thermal System